Pitting in One Area Only
Problem:
Printing an L shaped bracket that is experiencing pitting on one face/area only. The print quality around the rest of the print is great. Please see attached photos.
Printer/Settings:
Prusa MK3S+ (Latest Firmware 3.14.1)
Prusa Slicer 0.2mm Quality Settings (Version 2.9.5)
Thoroughly dried, new Geeetech black PETG (16+ hours in Sunlu S2 dryer at 65 degrees with venting to 15% humidity), 0.2mm layer height, 5 perimeters, 20% gyroid infill, 240 degrees print temp, 90 degrees bed temp, organic supports where needed. Fan speed 30-50%.
It is 85%-90%+ humidity/~16 degrees Celsius where I live (UK), but it has been dried in the dryer in a room with a dehumidifier.
Speed: 45mm/s perimeters, 25mm/s small/external perimeters.
Extrusion Multiplier and Linear Advance (0.05, vs Prusa default 0.08) are calibrated.
What I have tried to solve the problem:
Thoroughly dried the filament.
Checked Z seam is aligned (I used seam painting to force it into the desired corner)
I printed the first part and observed the pitting defects. I cleaned out extruder gears and tried again, with a marginal improvement.
Lots of researching!
I have ruled out the below, but I'm open minded about checking:
Filament is thoroughly dry - if it wasn't, I think I would get these pit marks all over the print
Partially clogged nozzle - if it was, I think I would get these pit marks all over the print
Confirm Z seam settings correct.
Possible clues:
Pit marks are only on this small perimeter section only
Pit marks are not present at the bottom and top 5mm of the print. Instead, pit marks are only present where the section is 'disconnected' from the rest of the bracket.
Possible retraction/deretraction/back pressure issue. Whilst users in the below links have experienced pitting due to mis-set retraction settings, they have all been on the Prusa Mini (bowden) and I'm hesitant to change them on my MK3S+ (direct drive) due to it's already much shower retraction compared to a Bowden machine.
The extruder idler tension screw was 0.5mm below flush. I have loosened it to 0.5mm above flush in line with Prusa documentation, but have not done a third print yet to test.
Helpful guides/others who have experienced similar issue:
Pitting guidance - https://www.reddit.com/r/FixMyPrint/comments/xpvu09/diagnosing_stringing_vs_branching_vs_pitting/
https://forum.prusa3d.com/forum/how-do-i-print-this-printing-help/issue-with-gaps-in-layers/
https://www.reddit.com/r/ender3/comments/104yckq/how_do_i_get_rid_of_these_pits_on_my_3d_prints/
https://forum.prusa3d.com/forum/postid/604692/
Request
I would be very grateful if anyone could offer suggestions, guidance, or similar experiences that they have had and possible solutions to this problem. Many thanks in advance!
RE: Pitting in One Area Only
P.S
I have corrected the tension of the X and Y axis belts
I notice a slight bulge/layer shift at top 5mm on the face with the pitting.
RE: Pitting in One Area Only
My core one does the same with some colors of ABS, but not with others (same brand).
Can't say I have a conclusive solution (other than "use spools that work or live with it").
https://forum.vorondesign.com/threads/whats-this-defect-abs.17446/
If that is just one pit per layer recheck your seam settings.
If you would like someone to review the part save your project as a .3mf file
Set up the slice then Files > Save Project as
Zip the .3mf and post it here. It will contain both your part and your settings for us to diagnose.
Cheerio,